On August 22, a British woman learned first-hand just how unreliable H&M's sizing can be.

Shopper Samantha Bell took a picture that juxtaposed a pair of UK size 16 (US size 12) jeans from H&M next to a pair in the same size from the budget British retailer Primark. She shared the photo, which we first saw on Yahoo Style, with members of the Free to be OK with me body positivity group on Facebook.

"I know I'm not the first person to raise this, but holy s---, H&M need to do something about their sizing. This is a size 16 from H&M (blue) vs a size 16 from Primark (black)," she wrote in the caption of her post.

Bell said that both pairs are a UK size 16 (or US size 12) skinny jeans, but that the H&M version is significantly smaller than Primark's. "I measured the difference. 14cm / 5.5inches [sic]. FOURTEEN CM!" she wrote in the comments of her post. "And yes, they're both the same style (skinny fit)."

Some members of the closed Facebook group were able to relate and shared their experiences at other stores in the comments of the post.

"Some shop's sizes are just ridiculous. I had to buy the largest pair they had in Topshop in jeans, made me feel awful even though I'm a petite 12 [a US size 8]," one woman wrote. "But depending on where I shop it can range from 12-16 [US sizes 8 - 12]. Like others have said just ignore the size label and see if it fits!"

"Shopping can be so frustrating and lots of leg work! But please don't define or value yourself what happens to be on hangers [sic] in fast/cheap (or any) clothing shops," another woman wrote in the comments.

Bell also sparked a conversation about sizing on Twitter.

A representative for H&M told INSIDER that the brand uses the same "global" sizing in 66 countries, and explained that because "there is no global mandatory sizing standard, sizes will differ between brands and different markets."

In a statement provided to INSIDER, the representative said the retailer frequently reviews its sizing: "Our dedicated, in-house sizing department works according to an average of the sizes and measurements suggested by the markets we operate in. H&M sizes are continually reviewed by our in-house sizing department."

The representative also addressed how the brand's sizing can make customers feel about themselves. "It is only ever our intention to design and make clothes that make our customers feel good about themselves, any other outcome is neither intended nor desired," the representative said.

The intention is not getting through to customers. This summer alone, women have called out H&M, Express, and American Eagle for implicitly fat-shaming them with inaccurate sizing. Fast-fashion brands simply need to be consistent and inclusive.

INSIDER contacted Bell for comment, but did not hear back at the time of this post.

Here's the full statement H&M provided to INSIDER:

"H&M hugely values all customer feedback. It is only ever our intention to design and make clothes that make our customers feel good about themselves, any other outcome is neither intended nor desired. H&M's sizes are global and the sizes offered in the UK are the same in all the 66 markets in which we operate in and online. As there is no global mandatory sizing standard, sizes will differ between brands and different markets. Our dedicated, in-house sizing department works according to an average of the sizes and measurements suggested by the markets we operate in. H&M sizes are continually reviewed by our in-house sizing department."